1. Field of the Invention
This invention relates to color sorters and, more particularly, to a color sorter for sorting pulse such as peanuts.
2. Description of the Related Art
Japanese Patent Application Kokai-Publication No. Sho No. 63-200878 discloses a color sorter of bichromatic type for sorting pulse. In this color sorter, pulse passing a detecting position continuously is illuminated from a light source, and an optical system which is provided in three directions measures and photoelectrically converts the difference between light reflected from the pulse and light from a reference color member (a background). When the detected difference signal thus obtained exceeds a predetermined level (a threshold value), the corresponding pulse is judged as abnormal color defective pulse, such as unripe pulse, worm-eaten pulse, etc. and the same is ejected by an ejector.
Japanese Patent Application Kokai-Publication No. Sho 63-315179 also discloses a color sorter of the same bichromatic type wherein the sorting accuracy is enhanced. In this color sorter, detecting positions are provided at two positions, i.e., above and below an ejector. Pulse which has been judged at the upper detecting position as normal pulse and passed the ejector without being ejected, is measured once again at the lower detecting position to check whether proper sorting has been done in the upper detecting position. If it is found that the sorting is improper, the result is fed-back to a controller so as to adjust or reset the threshold value for the upper detecting position. Thus, the sorting accuracy is enhanced.
In the sorting of pulse, the foreign matter that has been contained in the material pulse, such as earth, stones, grass, etc., can be comparatively readily removed using a specific gravity sorter, a wind sorter, etc. Further, defective pulse such as unripe pulse and worm-eaten pulse can be practically sufficiently removed by the conventional color sorters of bichromatic type noted above, which is based on the light reflected from a surface of the pulse. However, it is theoretically impossible to sort out moldy pulse as a kind of defective pulse, particularly internally moldy pulse in which mold exists inside the pulse, with the conventional bichromatic color sorters based on the reflected light. Further, externally moldy pulse with mold externally produced thereon could be sorted out insufficiently with the conventional color sorters based on the reflected light.
Afuratoxine produced on moldy pulse is a poison produced from mold. It is a kind of mycotoxine and is thought to be a cancer-inducing substance. Its dealing, therefore, is now an important problem all over the world. To effectively detect and remove such moldy pulse in the sorting of pulse, is thus very important for avoiding the poisonous matter and ensure safety of the food.